New Genotype of Coxiella burnetii Causing Epizootic Q Fever Outbreak in Rodents, Northern Senegal

In Senegal, Coxiella burnetii, which causes Q fever, has often been identified in ticks and humans near livestock, which are considered to be reservoirs and main sources of infection. We describe the emergence of C. burnetii in rodents, not previously known to carry this pathogen, and describe 2 new genotypes.

C oxiella burnetii is a causative agent of Q fever, a worldwide zoonosis. The disease may be acute (relatively benign) or chronic (with a wide range of clinical manifestations that can lead to high human mortality) (1). Humans are infected by inhaling contaminated environmental dust and aerosol particles from the birth products of infected animals, as well as through direct contact with milk, urine, or feces containing C. burnetii (2,3). Humans are not considered natural hosts of C. burnetii (4). A wide spectrum of animals can serve as hosts (4), but the reservoirs are livestock, mainly sheep, cattle, and goats (3), which are also the main sources of human infection (1).
In Senegal, C. burnetii has been reported in humans (4-6) and ticks (4). It has been isolated from rodent-associated soft ticks (Ornithodoros sonrai) and detected in several species of hard ticks collected from ruminants (4). Our previous study of zoonotic pathogens in rodents collected in 2017 revealed no presence of C. burnetii in rodent populations from the Ferlo region in northern Senegal (7). However, in this study, we tested rodent samples collected during 2019-2020 from the same region and found high prevalence of a new C. burnetii genotype, which might indicate an ongoing epizootic outbreak.
We screened 125 rodent samples for C. burnetii; the rodents were collected in the Ferlo region in northern Senegal near Widou Thiengoly (15.99°N, 15.32°W) under framework agreements between the French National Research Institute for Development and Senegal (7). None of the rodent species investigated were listed as protected with the International Union for Conservation of Nature or the Convention on International Trade in Endangered Species of Wild Fauna and Flora. Handling procedures were performed under Centre de Biologie Pour la Gestion des Populations agreement no. D-34-169-1 for experiments on wild animals and followed the guidelines of the American Society of Mammologists (8).
Our finding of C. burnetii MST75 and MST76 genotypes in the Ferlo rodent community suggests the emergence of a Q fever epizootic outbreak. Previously identified C. burnetii strains in Senegal were related to the proximity of livestock near the villages of Dielmo and Ndiop (9). In Ferlo, a previous study conducted on rodents sampled in 2017 did not find C. burnetii (7), indicating a relatively recent, possibly still ongoing epizootic outbreak. High C. burnetii prevalences (28%-38%) were observed in different species of gerbilline rodents, including G. nigeriae, which has recently colonized northern Senegal and is now the dominant species in outdoor rodent communities of Ferlo (10). The possibility of animal transmission from farms located near the rodent sampling area should also be explored. Our study shows the emergence in Senegal of new C. burnetii genotypes in susceptible animals, such as rodents (1), which might be a source of human infections. Although the pathogenicity of these new genotypes for humans is yet unknown, our findings signal the urgent need for epidemiologic surveillance for C. burnetii infection in humans in Senegal and neighboring countries.

RESEARCH LETTERS
New classes of antitubercular drugs, diarylquinolines and nitroimidazoles, have been associated with improved outcomes in the treatment of drug-resistant tuberculosis, but that success is threatened by emerging drug resistance. We report a case of bedaquiline and delamanid resistance in a 55-year-old woman in South Africa with extensively drug-resistant tuberculosis and known HIV.